Science
Astronomers Unveil 12 Billion Years of Supermassive Black Hole History
(CTN News) – Astronomers used X-ray data and complex supercomputer models to study the evolution of supermassive black holes over 12 billion years of cosmic history.
Scientists discovered that the black hole at the center of the Milky Way galaxy reached its four million solar masses relatively late in its lifetime.
Astronomers have struggled to understand the beginnings of supermassive black holes, which can be millions or billions of times more massive than our sun.
Astronomers Fan Zou and W. Niel Brandt, both from Penn State University, have now headed a team that has used observations and simulations to connect the two pathways of black hole formation. The results may finally provide some answers.
Zou presented their study at the 244th meeting of the American Astronomical Society in Wisconsin, raising the topic of how supermassive black holes evolve to such large sizes. “To address that, we need to track the overall growth history of these supermassive black holes.”
As previously stated, black holes grow via two basic mechanisms. The accretion of cold gas from their home galaxy is what causes one. This gas creates an accretion disc around the black hole, and stuff from it spirals towards its core.
The accretion disc can become so dense that friction between gas molecules heats it to millions of degrees, emitting X-rays. The other mechanism occurs when galaxies collide. When galaxies merge, their supermassive black holes fuse, causing a surge of gravitational waves.
The study team analyzed archival data from NASA’s Chandra X-ray Observatory, the European Space Agency’s XMM-Newton mission, and the eROSITA X-ray instrument on the joint German-Russian Spektr-RG spacecraft to determine the role of gas accretion in supermassive black hole growth.
The researchers were able to spot X-ray emissions coming from approximately 8,000 rapidly developing supermassive black holes.
“When supermassive black holes accrete the surrounding gas they emit strong X-rays, so by detecting them in the X-ray bands we can measure their accretion power,” Zou said.
Astronomers Supermassive black hole stories
They used the IllustrisTNG cosmological supercomputer simulation to model galaxy mergers throughout cosmic history. The scientists used X-ray data and simulated mergers to study the evolution of supermassive black holes across 12 billion years, from 1.8 billion years after the Big Bang to now.
These computer models “capture the overall large-scale structure [of the universe] but are also able to probe individual galaxies,” Zou stated.
According to Zou and Brandt, X-ray data reveal that accretion has been the primary driver of black hole expansion throughout cosmic history.
Furthermore, the more massive the galaxy, the faster its supermassive black hole develops through accretion. Simulations indicate mergers may impact black hole growth but are not the primary cause.
“Accretion dominates the supermassive black-hole growth in most cases, and mergers make some notable secondary contributions,” Zou stated.
These findings also indicate that supermassive black holes expanded rapidly earlier in the universe, with new ones often forming.
However, by roughly 7 billion years ago, the total number of supermassive black holes had remained rather stable, with few new ones developing. Mergers had a greater impact in later history, peaking in relevance to black-hole growth 4 billion years ago.
“We found that once the universe reaches about 40% of its age, the overall demography of supermassive black holes is very similar to the demography of supermassive black holes that we see in the local universe,” Zou stated.
Astronomers modeled our galaxy’s black hole, Sagittarius A*, and found that most of its mass formed later in cosmic time. The Milky Way’s development was primarily due to accretion, with most mergers with other galaxies occurring over 8–10 billion years ago.
The European Space Agency’s Gaia mission discovered evidence of a dwarf galaxy colliding with the Milky Way 2-3 billion years ago.
Dwarf galaxies are thought to contain intermediate-mass black holes that are tens to hundreds of thousands of times the mass of our sun, and one may combine with Sagittarius A* to increase our black hole’s mass.
Because the data only go back 1.8 billion years after the Big Bang, they don’t explain how the seeds of supermassive black holes arose. Cosmologists face a problem, as the Hubble Space Telescope and James Webb Space Telescope have discovered enormous black holes earlier in the universe.
It’s unclear how they became millions of times the mass of our sun in less than a billion years.
A study on the findings was published in March in The Astrophysical Journal, and a second paper is currently being prepared.
Science
Australia Asks Residents to Catch Deadly Funnel Web Spider
As summer approaches in Australia, residents are warned to look out for the funnel web spider, one of the country’s deadliest species.
In addition to advising the public to avoid funnel-web spiders during mating season, the Australian Reptile Park in New South Wales has even asked people to capture live funnel-web spiders so they can “milk” their venom.
Native to eastern Australia, the funnel web spider can kill humans in as little as fifteen minutes if they do not receive medical treatment for its poisonous bite.
There have been thirteen fatalities attributable to this species, but none since the development of antivenom in 1981. The Australian Reptile Park is appealing to the public for assistance capturing and donating spiders, as the serum relies on milking live spiders.
Hunting for the funnel net spider in residential areas is common practice after a particularly wet and warm season. Look for spiders in cool, dark places like pools, garden residue, heaps of dirty clothing, and outside shoes.
Australian Reptile Park spider keeper Emma Teni recently blogged about how they rely on spider donations more than ever, especially now that breeding season has arrived and the temperature is perfect.
“Male funnel-web spiders have short lifespans, and with approximately 150 spiders required to make just one vial of antivenom, we need the public’s help to ensure we have enough venom to meet demand.”
“If you spot an egg sac while collecting a spider, it’s important to safely collect that as well,” said Teni. “It can provide a robust supply of healthy young spiders to aid in our antivenom production.”
The spiders won’t be able to climb plastic or glass, but Teni suggests capturing funnel webs in a wide-mouthed jar with a cover. Then, you can lead the spiders into the container using a long spoon or something similar.
After that, fill the jar with moist soil, screw on the top, and bring it to the designated drop-off spot.
“We depend on the public for spider donations, and we want to make sure everyone stays safe during the collection process, especially with conditions being so favourable this year,” said Teni.
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Science
A Spacecraft Is On Its Way To A Harmless Asteroid Slammed By NASA In A Previous Save-The-Earth Test
CAPE CANAVERAL, Florida – A spacecraft launched Monday to probe the site of a cosmic accident.
The European Space Agency’s Hera spacecraft launched on a two-year trip to the little, harmless asteroid slammed by NASA two years ago as a practice run for the day when a murderous space rock threatens Earth. It’s the second phase of a planetary defense experiment that could one day save the globe.
SpaceX’s Falcon rocket vanished with Hera into the late morning clouds. An hour later, cheering erupted in the control center in Germany as the spacecraft split from the rocket’s upper stage and returned home. “It’s an amazing day,” the space agency’s director general, Josef Aschbacher, said later.
The 2022 crash of NASA’s Dart spacecraft reduced Dimorphos’ orbit around its larger companion, indicating that if a harmful rock was heading our way, it might be pushed off course with adequate warning.
A Spacecraft Is On Its Way To A Harmless Asteroid Slammed By NASA In A Previous Save-The-Earth Test
Scientists are eager to analyze the aftermath of the impact up close to determine how effective Dart was and what improvements may be required to protect Earth in the future.
“The more detail we can glean the better as it may be important for planning a future deflection mission should one be needed,” University of Maryland astronomer Derek Richardson stated before launch.
Researchers want to know if Dart (short for Double Asteroid Redirection Test) created a crater or changed the 500-foot (150-meter) asteroid more dramatically. It seemed to be a flying saucer before Dart’s blow and may now resemble a kidney bean, according to Richardson, who participated in the Dart mission and is assisting Hera.
Dart’s wallop sent rubble and boulders hurtling off Dimorphos, adding to the impact’s momentum. For months, the debris track extended thousands of miles (almost 10,000 kilometers) into space.
According to flight director Ignacio Tanco, some rocks and debris may still be hovering about the asteroid, posing a threat to Hera.
A Spacecraft Is On Its Way To A Harmless Asteroid Slammed By NASA In A Previous Save-The-Earth Test
“We don’t really know very well the environment in which we are going to operate,” Tanco informed me. “But that’s the whole point of the mission is to go there and find out.”
European authorities refer to the $400 million (363 million euros) effort as a “crash scene investigation.”
“Hera is going back to the crime scene and getting all the scientific and technical information,” said project manager Ian Carnelli.
Carrying a dozen science instruments, the compact car-sized Hera must swing past Mars in 2025 for a gravitational boost before landing at Dimorphos by the end of 2026. It’s a moonlet of Didymos, the Greek word for twin, a five-times larger asteroid that spins quickly. At that point, the asteroids will be 120 million miles (195 million kilometers) from Earth.
Hera will attempt to enter orbit around the rocky duo, progressively reducing flyby distances from 18 miles (30 kilometers) to a half-mile (1 kilometer). The spacecraft will examine the moonlet for at least six months to determine its mass, shape, composition, and orbit around Didymos.
Before the crash, Dimorphos circled its larger partner from three-quarters of a mile (1,189 meters) away. Scientists believe the orbit has become tighter and more oval-shaped, and that the moonlet may be tumbling.
Two shoebox-sized Cubesats will launch from Hera for even closer drone-like examinations, with one employing radar to peek beneath the moonlet’s boulder-strewn surface. Scientists believe Dimorphos was produced from particles shed by Didymos. The radar measurements should assist in determining whether Didymos is the small moon’s parent.
A Spacecraft Is On Its Way To A Harmless Asteroid Slammed By NASA In A Previous Save-The-Earth Test
After their survey, the CubeSats will attempt to land on the moonlet. If the moonlet tumbles, the situation will become more complicated. Hera may potentially conclude its mission with a perilous touchdown but on the bigger Didymos.
Asteroids, which are remnants of the solar system’s origin 4.6 billion years ago, circle the sun principally between Mars and Jupiter in what is known as the main asteroid belt, where millions of them live. When they fall from the belt and land in our area, they become near-Earth objects.
NASA now has around 36,000 near-Earth objects, the majority of which are asteroids, although there are also some comets. More than 2,400 of them are deemed potentially dangerous to the Earth.
SOURCE | AP
Science
A Rare Comet Brightens The Night Skies In October
NEW YORK — Prepare to spot a rare and dazzling comet.
The space rock is hurling toward Earth from the far reaches of the solar system and will make its closest approach on Saturday. It should be visible through the end of October, assuming clear skies.
A Rare Comet Brightens The Night Skies In October
Comet Tsuchinshan-Atlas should be visible to the naked eye, but binoculars and telescopes will provide a clearer view.
“It’ll be this fuzzy circle with a long tail stretching away from it,” explained Sally Brummel, planetarium manager at the Bell Museum in Minnesota.
What is a comet?
They are frozen remains from billions of years ago when the solar system was formed. They heat up as they swing toward the sun, revealing their distinctive streaming tails.
In 2023, a green one that had last visited Earth 50,000 years ago flew past again. Other significant flybys were Neowise in 2020 and Hale-Bopp and Hyakutake in the mid to late 1990s.
Where did Tsuchinshan-Atlas come from?
Also known as C/2023 A3, was found last year and named after the observatories in China and South Africa that spotted it.
It originated in the Oort Cloud, which extends far beyond Pluto. After making its closest approach to Earth at 44 million miles (71 million kilometers), it will not return for another 80,000 years, provided it survives the journey.
A Rare Comet Brightens The Night Skies In October
Every year, several comets are detected, but many of them burn up near the sun or are too far away to be observed without special equipment, according to Larry Denneau, a key researcher with the Atlas telescope that helped discover it.
How to View
Those seeking to see Tsuchinshan-Atlas should go outside about an hour after sunset on a clear night and look to the west.
The comet should be visible from both the Northern and Southern Hemispheres.
SOURCE | AP
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